Landslides in India and related issues

Reference

Landslides triggered by cyclonic rains in the Northeast have highlighted the need for resilience to disasters. About 13% of India's area, spread across 15 states and four union territories, is prone to landslides.

What is Landslide

• The sudden sliding of rocks, stones, soil or debris from a slope is called a landslide.
• A landslide is a type of “mass collapse” involving the downward movement of soil and rock under the direct influence of gravity.
• Landslides are mainly caused by local causes. Therefore, collecting data about landslides and estimating their probability is not only difficult but also very expensive.
• Landslides are broadly classified into three types
  • Type of material involved in the landslide e.g. rock, debris, soil, loose soil.
  • The type of movement of the displaced material such as fall, overturning, sliding, rotational sliding or translational sliding or sinking.
  • Depending upon the type of flow of the material such as rapid movement, viscous flow with a downward slope or slow (almost steady) flow.

Subsidence of land

• Land subsidence is the gradual settling or sudden sinking of the Earth's surface due to the removal or displacement of sub-surface material.
• This is often due to water, oil, natural gas or mineral resources being removed from the ground by pumping, fracking or mining activities.
• In addition, subsidence may also be caused by natural phenomena such as earthquakes, soil compaction, glacial isostatic adjustment, erosion, sinkhole formation, and water mixing with wind-deposited fine soil (loess deposits).
• The recent incident of Joshimath can be seen as an example of land subsidence.

What could be the possible causes of landslides?

• The causes of landslides can be classified into two parts: natural factors and man-made factors.

Natural factors

• Geological conditions: India has diverse landforms such as soft rocks, steep slopes and unstable soil conditions. These landforms are prone to sliding due to gravity which leads to landslides.
  • The Himalayan mountain range, created by the convergence of the Indian and Eurasian plates, is under constant pressure, making it prone to landslides and earthquakes.
  • Apart from the Nilgiris, landslides of a different type characterised by lateritic caps on steep slopes on the Konkan coast pose a frequent threat to the Western Ghats in the south, as well as to the western coast.
• Earthquakes: India is located in a seismically active zone and earthquakes can cause landslides by destabilizing slopes.
• Heavy rainfall: India receives heavy rainfall during monsoons, which can saturate the soil and increase its weight, reducing its strength and causing landslides.
• Soil erosion: Natural erosion of slopes caused by wind and water can weaken the soil, making it more vulnerable to landslides.

Anthropogenic Factor

• Deforestation: Cutting down trees and vegetation reduces slope stability and increases soil erosion, which may lead to landslides.
• Mining activities: Mining operations can destabilise slopes and cause landslides through blasting, excavation, soil and rock erosion.
• Construction activities: Improper construction practices, such as improper grading or digging can destabilize slopes and cause landslides.
• Land use changes: Land use changes, such as urbanization, can increase impervious surfaces, which may impede soil absorption of water and increase runoff, potentially leading to landslides.
• Water management: Poor water management, such as improper dam operation or improper drainage, can increase water pressure on slopes and reduce stability, which may trigger landslides.

What can be the impact of a landslide?

Social Impact

• Loss of life and property: Landslides can cause loss of life and property of people living in affected areas.
  • In many cases, landslides occur suddenly, giving people no or very little time to evacuate, which makes the situation even worse.
• Displacement of communities: Landslides can force people to evacuate their homes, leading to temporary or permanent displacement.
  • This can have significant social impacts, particularly on vulnerable groups such as women, children and the elderly.

Economic impact

• Agricultural sector: In rural areas, where agriculture is the main source of income, damage to crops, livestock and infrastructure can reduce incomes and increase food insecurity.
• Damage to infrastructure: Landslides can damage roads, bridges, buildings and other infrastructure, disrupting transportation and communication networks.
• Loss of tourism revenue: Landslides can also affect the tourism industry in India, especially in areas known for their natural beauty or cultural heritage.

Environmental degradation

• Landslides can cause significant environmental damage, including soil erosion, deforestation, and loss of biodiversity.
• Apart from this, wildlife can also be negatively affected by such a disaster.

Landslide Vulnerability of India

• India is ranked among the top five landslide-prone countries globally, with at least one death reported per 100 square kilometres due to landslide occurrence every year.
• According to the Geological Survey of India (GSI), about 0.42 million sq km (about 13%) of India's land area spread across 15 states and four union territories is vulnerable to landslides.
  • It covers almost all the hilly areas of the country, with about 0.18 million sq km (42% of the vulnerable area) in the North-Eastern region, where most of the terrain is mountainous.
  • About 66.5 per cent of landslide incidents are reported from the Northwestern Himalayas, about 18.8 per cent from the Northeastern Himalayas and about 14.7 per cent from the Western Ghats.
  • The area is also prone to earthquakes, which are a major cause of landslides.
• According to government data, between 2015 and 2022, 378 major landslides were recorded in eight states in the region, including Sikkim.
  • Across the country, Kerala recorded the highest number of landslides (2,239), most of them after the devastating floods of 2018.

What efforts are being made to deal with landslides?

Landslide Atlas

It is released by the Indian Space Research Organisation (ISRO). Its applications include-

• Disaster Management: Landslide atlas can be used to identify landslide prone areas and take preventive measures to avoid loss of life and property.
• Land use planning: The atlas can be used to identify areas that are unsuitable for development or human habitation because of the risk of landslides.
• Infrastructure planning: It can be used to plan the construction of infrastructure such as roads, railways and buildings in landslide-safe areas.
• Geological studies: This can help geologists study the causes of landslides and the factors contributing to the respective event.
• Research: The atlas can be used as a reference for research on landslides and related topics such as climate change, soil erosion and natural disasters.

National Disaster Management Authority (NDMA) Guidelines

• Hazard Mapping: NDMA recommends the preparation of landslide hazard maps, which can help identify landslide hazard areas and guide land use planning and development activities.
• Early warning systems: The NDMA emphasises the need for early warning systems that can provide alerts about impending landslides, allowing people to evacuate and take other precautionary measures.
• Land-use planning: Development activities should take into account landslide risks, and appropriate measures should be taken to mitigate the risks.
• Slope stabilization: This may involve building retaining walls or planting more trees to strengthen soil grip.
• Preparation: Keep drains clean, inspect drains, do not allow garbage, leaves, plastic bags, debris etc. to accumulate.
  • Identify areas of rock falls and building collapse, cracks indicating landslides, and immediately report any signs of landslides to the responsible authority.
• Post-landslide measures: NDMA recommends that post-landslide measures should be taken to restore essential services and infrastructure as well as provide assistance to affected communities.
  • Undertake site-specific studies of major landslides and plan remediation measures and encourage State Governments to implement these measures.

The way forward

• Early warning systems: The government should continue to invest in early warning systems that can alert people living in landslide-prone areas.
• Infrastructure development: The government should focus on developing landslide resilient infrastructure.
  • This may include building retaining walls, stabilising slopes and improving drainage systems and constructing stronger roads and bridges.
• Afforestation: Afforestation and sustainable land use should be promoted in landslide prone areas.
• Research and mapping: More research and mapping should be invested in to identify areas most vulnerable to landslides.
• Disaster Management Planning: Plans should be regularly reviewed and updated to ensure that they remain relevant to the changing scenario and the needs of local communities.
• Community awareness and capacity building: The government should provide training to local communities on landslide risks and ways to prevent and manage them, emergency response, early warning systems and sustainable land use practices.

Conclusion

A multi-pronged approach is needed to reduce landslides in India that includes investment in infrastructure, reforestation, sustainable land use practices, research and community participation. In this regard, emphasis will also have to be laid on landslide atlases and early warning systems as well as new innovations that can qualitatively improve the quality of life of the affected people.